The invention relates to a mechanism for registering sheets of different sizes relative to a station.
Sheet registration mechanisms of various kinds are known in the art. For example, U.S. Pat. No. 4,660,819, issued Apr. 28, 1987 in the names of C. Allocco et al, discloses a sheet registration device in a document handler of the kind used with electrographic copying apparatus wherein a set of document sheets are recirculated one or more times from the tray to a copying position and then returned to the tray. The handler of the patent has a tray surface on which sheets rest, and a sidewall or guide along one side edge of the tray surface terminates in an inclined ramp at the surface. A similar inclined ramp is provided on the other side of the tray. The two ramps are generally parallel to each other along opposite side edges of the tray. These ramps assist in registration of the document sheets in a corner of the tray prior to feeding of the sheets to the copying position.
Known sheet registration mechanisms may require a force other than gravity to be used for proper positioning of the sheet in the registration mechanism. In the above-mentioned patent, for example, an air knife provides a jet of air which assists in locating the sheet on the tray surface. Also known, registration mechanisms require delivery of sheets to the mechanism from only one side, and such can limit the use of the mechanisms to specific kinds of apparatus.
In the related patent application entitled "Film Sheet Registration Mechanism," referenced above, a mechanism registers a sheet of film and advances it toward an imaging station. A registration member is located along a surface that receives the sheet, and the member is engageable by an edge of the sheet for registering and guiding the sheet toward the station. An urging guide located along another portion of the surface is skewed relative to the registration member and spaced from it so that the end portions of the guide and registration member nearest the station are spaced apart sufficiently to enable the sheet to lie flat on the surface while other portions thereof are sufficiently close together to prevent the sheet from lying flat on the surface. The guide projects above the surface and is tilted away from the registration member so that the guide imparts a component of force onto a sheet resting thereon which urges the sheet toward the registration member. In order to accommodate sheets of various sizes, movable guides pivot between a lowered position wherein they are recessed in the surface of the platen, and a raised position above the surface. When in the raised position, the movable guides are parallel to the urging guide and enable smaller sheets to be urged toward the registration member, and when in the lowered position they are substantially in the plane of the platen.